1. Field of the Invention
The present invention relates to a display device having multiple viewing zones.
2. Discussion of the Related Art
In general, display devices display an image in common over viewing directions, and viewers watch the same image through the display device. This type of display device has disadvantage when viewers want to watch different images. Recently, a navigation device has had multiple functions such as a navigation mode, an image display mode, and the like. When the navigation mode is operated, one at a passenger seat who wants to watch like moving images could not do. Accordingly, recently, multi-view mode display devices, which can simultaneously display multiple images at multiple viewing zones, have been suggested to provide viewers with different images according to different viewing zones. FIG. 1 is a schematic view illustrating a multi-view mode display device having dual viewing zones according to the related art.
Referring to FIG. 1, the display device 1 according to the related art includes a display panel 10 and a parallax barrier 20. The display panel 10 includes a plurality of sub-pixels SP. The parallax barrier 20 includes a transmissive portion T and a blocking portion B arranged alternately in order that different sub-pixels SP are selectively viewed according to positions. Accordingly, viewers u1 and u2 at different viewing zones see different images.
The parallax barrier 20 selectively passes and blocks lights so that the left viewer u1 at a first viewing zone sees lights from sub-pixels SP displaying left image data L among lights from all sub-pixels SP while the right viewer u2 at a second viewing zone sees lights from sub-pixels SP displaying right image data R among lights from all sub-pixels SP.
An image displayed through the multi-view mode display device displaying multiple images has a resolution less than through an image displayed by a single view mode display device displaying an image in common. For example, the dual view mode display device is supplied with two original image data. Each original image data supplied have data amounts to be displayed through the single view mode display device. However, to simultaneously display dual images through the dual view mode display device, each original image data are sampled and have a data amount less than an original data amount, and the dual view mode display device displays the dual images with the two sampled image data. Accordingly, the viewer can not see some parts not sampled out of the original image, and resolution of the image viewed through the dual view mode display device is reduced.
FIG. 2 is a view illustrating a method of inputting first and second original image data into a display panel of a dual view mode display device according to the related art. In FIG. 2, each of the first and second original image data inputted to the display device is shown in a matrix form in view of mapping each of the first and second original image data into a single view mode display device. It is assumed that each of the first and second original image data have pixel image data of 6*3 in horizontal and vertical pixel resolutions, and the display panel has pixels of 6*3 in horizontal and vertical pixel resolutions and 18*3 in horizontal and vertical sub-pixel resolutions.
Referring to FIG. 2, the display panel (10 of FIG. 1) of the dual view mode the display device (1 of FIG. 1) includes a plurality of pixels arranged in horizontal and vertical directions. Each pixel includes red (R), green (G) and blue (B) sub-pixels arranged in a horizontal direction. Sub-pixels R, G or B having the same color are arranged in a vertical direction. The pixel has a square shape, and the sub-pixel has a rectangular shape having a ratio of width to length, 1:3.
The display panel has the same configuration of the pixels and sub-pixels as the configuration of each of the first and second original image pixel and sub-pixel data, the display panel should have image data sampled among each of the first and second original image data. For example, sub-pixels at odd (o) columns with respect to sub-pixel of the display panel are supplied with image data sampled among the first original image data for a first viewing zone. Further, sub-pixels at even (e) columns with respect to sub-pixel of the display panel are supplied with image data sampled among the second original image data for a second viewing zone.
Accordingly, half of each of the first original image data and the second original image data are selected and inputted to the corresponding sub-pixels. For example, image data at odd columns with respect to sub-pixel among the first original image data are selected and inputted to the sub-pixels at odd columns with respect to sub-pixel of the display panel while image data at even columns with respect to sub-pixel among the second original image data are selected and inputted to the sub-pixels at even columns with respect to sub-pixel of the display panel. Accordingly, the display panel simultaneously displays dual images through the sub-pixels at odd and even columns, respectively.
FIGS. 3A and 3B are views illustrating first and second images viewed at first and second viewing zones, respectively, using the display device according to the related art.
Referring to FIGS. 3A and 3B, since the parallax barrier (20 of FIG. 1) is located on the display panel, the sub-pixels at odd columns supplied with the sampled first original image data are viewed at the first viewing zone while the sub-pixels at even columns supplied with the sampled second original image data are viewed at the second viewing zone.
At each of the first and second viewing zones, one of adjacent two sub-pixels of the display panel is viewed. Accordingly, a pixel of an image viewed at each viewing zone seems to have an area occupied by six sub-pixels in a horizontal direction. Accordingly, a vertical resolution of the image viewed at each viewing zone is the same as the vertical resolution of the original image. However, a horizontal resolution of the image is half of the horizontal resolution of the original image. Accordingly, resolution of the image viewed at each viewing angle is reduced sharply. In other words, each of the first and second original images has a resolution of 6*3 while each of the images viewed at the first and second viewing zones has a resolution of 3*3. The horizontal resolution is reduced more as the display device has more viewing zones.
FIG. 4 is a view illustrating a method of attaching a parallax barrier to a display panel according to the related art.
Referring to FIG. 4, a display panel 10 includes first and second substrates 11 and 12. A parallax barrier 20 is attached to the second substrate 12 of the display panel 10. To transmit multiple images to corresponding viewing zones, a predetermined thickness of the second substrate, which is a distance between the pixels of the display panel 10 and the parallax barrier 20, is required. The distance between the pixels and the parallax barrier 20 is proportional to a pitch i.e., a distance between sub-pixels in a horizontal direction for the same viewing zone. The pitch in the related art, for example, a distance by two sub-pixels as shown in FIG. 2 is very short. Accordingly, the short distance between the pixels and the parallax barrier 20 i.e, the small thickness of the second substrate 12 is required, and the second substrate 12 is required to be removed much. Further, as the display device have recently had the high definition, the second 12 is required to have the smaller thickness and to be removed more. However, since a process of removing the second substrate made of a material such as glass is very difficult, many problems occur as removing amount of the second substrate 12 increases. For example, when a polishing method is used to remove the top portion of the second substrate 12 shown as a dashed line in FIG. 4, uniformity of removing is reduced and the removed surface of the second substrate 12 is uneven. Accordingly, transmissive and blocking portions TA and BA of the parallax barrier 20 may be located at undesired position, and thus desired images may not be transmitted to the corresponding zones. Further, some portions are excessively removed, and thus holes sometimes occur.
Further, protruded portion of the first substrate 11, at which a pad portion connected to a driving circuit is located, has defect or loss during the removing process.
Further, since the remaining thickness of the second substrate 12 is very thin, a breakage of the second substrate 12 occurs when pressure is applied to attach the parallax barrier 20 to the display panel 10.